UNIVERSITY  OF  CALIFOBNIA  PUBLICATIONS 

COLLEGE  OF  AGRICULTURE 

AGRICULTURAL  EXPERIMENT  STATION 

BERKELEY,  CALIFORNIA 


GREEN    MANURE   CROPS    IN 
SOUTHERN  CALIFORNIA 


BY 

W.  M.  MERTZ 


BULLETIN  No.  292 

February,  1918 


UNIVERSITY  OF  CALIFORNIA  PRESS 
BERKELEY 

1918 


Benjamin  Ide  Wheeler,  President  of  the  University. 

EXPERIMENT  STATION  STAFF 

HEADS   OP   DIVISIONS 

Thomas  Forsyth  Hunt,  Director. 
Edward  J.  Wickson,  Horticulture  (Emeritus). 

Herbert  J.  Webber,  Director  Citrus  Experiment  Station;  Plant  Breeding. 
Hubert  E.  Van  Norman,  Vice-Director ;  Dairy  Management. 
William  A.  Setchell,  Botany. 
Myer  E.  Jaffa,  Nutrition. 
Charles  W.  Woodworth,  Entomology. 
Ralph  E.  Smith,  Plant  Pathology. 
J.  Eliot  Coit,  Citriculture. 
John  W.  Gilmore,  Agronomy. 
Charles  F.  Shaw,  Soil  Technology. 

John  W.  Gregg,  Landscape  Gardening  and  Floriculture. 
Frederic  T.  Bioletti,  Viticulture  and  Enology. 
Warren  T.  Clarke,  Agricultural  Extension. 
John  S.  Burd,  Agricultural  Chemistry. 
Charles  B.  Lipman,  Soil  Chemistry  and  Bacteriology. 
Clarence  M.  Haring,  Veterinary  Science  and  Bacteriology. 
Ernest  B.  Babcock,  Genetics. 
Gordon  H.  True,  Animal  Husbandry. 
James  T.  Barrett,  Plant  Pathology. 
Fritz  W.  Woll,  Animal  Nutrition. 
Walter  Mulford,  Forestry. 
W.  P.  Kelley,  Agricultural  Chemistry. 
H.  J.  Quayle,  Entomology. 
J.  B.  Davidson,  Agricultural  Engineering. 
Elwood  Mead,  Rural  Institutions. 
H.  S.  Reed,  Plant  Physiology. 
W.  L.  Howard,  Pomology. 
fFRANK  Adams,  Irrigation  Investigations. 
C.  L.  Roadhouse,  Dairy  Industry. 
O.  J.  Kern,  Agricultural  Education. 
John  E.  Dougherty,  Poultry  Husbandry. 
S.  S.  Rogers,  Olericulture. 
R.  S.  Vaile,  Orchard  Management. 
J.  G.  Moodey,  Assistant  to  the  Director. 
W.  M.  Mertz,  Superintendent  of  Cultivations. 
Mrs.  D.  L.  Bunnell,  Librarian. 


t  In  co-operation  with  office  of   Public   Roads   and  Rural   Engineering,   U.    S. 
Department  of  Agriculture. 


GREEN  MANURE  CROPS  IN  SOUTHERN 
CALIFORNIA* 


By  W.  M.  MERTZ 


INTRODUCTION 

In  a  comparison  of  factors  governing  agricultural  practice  in 
humid  climates  and  in  a  semi-arid  section  as  southern  California,  the 
two  most  striking  differences  are  apparent  in  connection  with  the 
moisture  content  and  the  organic  content  of  the  soil.  The  develop- 
ment of  successful  agriculture  under  this  semi-arid  condition  depends 
in  large  measure  upon  supplying  the  deficiencies  in  water  and  organic 
material.  In  the  case  of  water,  the  question  resolves  itself  into  two 
factors:  first,  is  there  an  available  source  of  water;  and  if  so,  can  it 
be  put  upon  the  land  at  a  cost  which  the  returns  from  the  crop  will 
warrant?  The  question  of  maintaining  the  supply  of  organic  material 
in  the  soil  after  the  water  has  once  been  applied  to  the  land  is  the 
next  most  vital  problem.  Agricultural  soils  of  semi-arid  regions  are 
notably  deficient  in  organic  matter.  One  of  the  chief  concerns  of 
the  farmer  is  to  obtain  soil  organic  matter  cheaply  in  order  to  main- 
tain a  supply  in  the  soil  sufficient  for  the  needs  of  the  crops  to  be 
grown.  Two  methods  present  themselves :  the  first,  that  of  incorpo- 
rating into  the  soil  various  animal  manures  and  waste  products ;  the 
second,  that  of  plowing  under  green  manures  grown  in  rotation  with 
field  crops,  or  between  the  rows  of  orchard  trees. 

Where  the  supply  of  organic  matter  is  low,  there  is  usually  a 
corresponding  lack  of  nitrogen.  Thus  the  two  problems  of  increasing 
the  organic  matter  and  increasing  the  nitrogen  content,  are  closely 
bound  together.  The  use  of  animal  manures  tends  to  accomplish 
both  of  these  objects.  Complications  arise,  however,  in  the  way  of 
expense,  for  only  a  very  small  percentage  of  our  farmers  are  stock- 
raisers,  and  many  orchardists  do  not  even  keep  their  own  work  teams. 
It  thus  becomes  necessary  for  the  orchardist  to  buy  a  very  large 
proportion  of  the  animal  manures  used.  Under  the  increasing  de- 
mand, these  manures  have  advanced  in  price  and  are  available  only 
in  limited  quantities. 

1  Paper  no.  46,  University  of  California,  Citrus  Experiment  Station,  River- 
side, California. 


4  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

The  question  naturally  arises,  cannot  legumes  be  found  that  would 
be  suitable  for  green  manuring,  the  use  of  which  would  maintain  both 
the  organic  and  nitrogen  contents  of  the  soil?  For  several  years 
attempts  were  made  to  use  various  legumes  as  green-manure  crops, 
especially  in  citrus  orchards.  After  quite  extensive  trials,  growers 
in  general  adopted  two  species,  spring  vetch  (Vicia  sativa),  and 
Canada  peas  (Pisum  arvense).  This  practice  was  based  largely  upon 
the  fact  that  the  seed  of  these  two  plants  was  obtainable  in  large 
quantities  at  reasonable  prices  and  that  both  crops  gave  heavy  yields 
of  organic  material.  Of  late  years,  these  legumes  have  not  been 
giving  entire  satisfaction  and  are  going  out  of  use  in  large  measure. 
This  state  of  affairs  emphasized  the  necessity  for  finding  other  legumes 
better  adapted  to  the  conditions.  Since  a  tendency  was  shown  to 
revert  to  cereals  as  green-manure  crops,  it  seemed  advisable  to  attempt 
to  verify  under  local  conditions  the  findings  of  eastern  writers  on 
the  relative  values  of  legumes  and  non-legumes. 

This  publication  has  three  objects : 

1.  To  give  the  results  of  a  six-year  experiment  on  the  relative 
effects  of  different  green-manure  crops,  including  both  legumes  and 
non-legumes. 

2.  To  bring  up  to  date  the  results  of  a  ten-year  experiment  with 
green-manure  crops  in  a  citrus  orchard. 

3.  To  bring  together  the  experimental  and  observational  data  on 
the  subject  of  green  manuring  in  general. 


A.     WINTER   GREEN-MANURE    CROPS    IN    ANNUAL   ROTATIONS    WITH    CERTAIN 

FIELD  CROPS 

OBJECT  OF  EXPEEIMENT 

The  objects  of  this  experiment  were : 

1.  To  determine  the  relative  value  of  a  number  of  legumes  as 
measured  by  their  ability  to  produce  consistently  heavy  yields  under 
fall  and  winter  conditions. 

2.  To  determine  the  relative  value  of  a  number  of  different  legumes 
and  non-legumes  as  green-manure  crops,  when  measured  by  their 
effect  on  the  yields  of  annual  field  crops  following  them. 

3.  To  determine  the  fertilizing  value  of  legume  green  manures  in 
comparison  with  commercial  forms  of  nitrogen  when  added  in  con- 
junction with  cereal  green  manures. 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA 


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UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


HISTOEY 

The  experiment  herein  outlined  was  started  at  Riverside  by  the 
University  of  California,  Citrus  Experiment  Station.  The  prelim- 
inary work  was  under  the  direction  of  J.  H.  Norton.  Since  1912,  the 
work  has  been  under  the  supervision  of  the  author.  A  tract  of  land 
on  the  Rubidoux  Experimental  Farm  at  Riverside,  California,  was 
divided  into  tenth-acre  plots,  and  so  arranged  that  each  plot  was 
irrigated  separately.  These  were  numbered  consecutively  from  west 
to  east.  The  soil  is  a  light  Sierra  sandy  loam,  tending  to  become 
somewhat  heavier  on  the  east  side  of  the  block. 


OUTLINE    OF   EXPEEIMENT 

In  the  execution  of  this  experiment,  the  tract  of  land  used  was 
divided  into  seventeen  plots,  each  20  feet  wide  by  218  feet  long, 
containing  approximately  one-tenth  of  an  acre.  These  were  numbered 
consecutively  1  to  17.  The  plan  of  the  experiment  was  to  grow  differ- 
ent green-manure  crops  on  these  plots  during  the  winter  months. 
During  the  summer  following,  certain  indicator  crops,  such  as  corn 
and  potatoes,  were  to  be  grown  in  solid  blocks  crossing  the  plots  and 
serve  by  their  growth  and  yield  to  demonstrate  the  comparative  value 
of  the  different  treatments  applied  to  the  plots. 

The  plots  indicated  by  the  odd  numbers  have  all  had  some  variety 
of  legume  grown  on  them  each  winter  and  turned  under  as  a  green 
manure  in  the  spring.  The  plots  of  even  numbers  have  had  non- 
leguminous  plants  grown  and  turned  under.  Certain  of  these  non- 
legume  plots  were  fertilized  with  commercial  nitrogenous  materials 
during  the  growth  of  the  indicator  crop,  thus  furnishing  some  means 
of  comparing  the  value  of  nitrogen  from  the  leguminous  manure  crop 
with  known  quantities  of  nitrogen  from  commercial  fertilizer. 

The  treatment  given  each  plot  was  as  follows : 

Plot  1. — Common  vetch  (Vicia  sativa).     (Fig.  1.) 

Plot  3. — Bur  clover  (Medicago  hispida  denticulate) . 

Plot  5. — Crimson  clover  (Trifolium  incarnatum) ,  during  the  first 
three  years  of  experiment.  This  crop  failed  to  germinate  in  every 
case,  and  in  the  winters  of  1913-1914  and  1914-1915,  the  plot  was 
sown  to  purple  vetch  (Vicia  atropurpurca) .     (Figs.  1  and  3.) 

Plot  7. — Wild  lupine  for  the  first  year.  This  failed  to  germinate, 
and  beginning  with  the  winter  of  1910-1911,  the  plot  has  had  bitter 
vetch  (Vicia  erviUa)  grown  upon  it. 


GREEN   MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  7 

Plot  9. — Canada  field  peas   (Pisum  arvense).     (Fig.  3.) 

Plot  11. — Tangier  peas  (Lathyrits  tingitanus). 

Plot  13. — Soja  beans  for  first  year.  This  proved  to  be  too  tender 
for  a  winter  crop,  and  beginning  with  the  winter  of  1910-1911,  bitter 
clover  (Melilotvs  indica)  has  been  grown  upon  this  plot.  (Figs.  1 
and  2.) 

Plot  15. — Fenugreek  (Trigonella  Foenum-Oraecum) . 

Plot  17. — Lentils    (Lens  esculenta). 

The  plots  with  even  numbers  have  had  growing  upon  them  each 
year  the  same  non-legume.  Different  crops  have  been  used  during 
the  several  years.  In  the  winter  1909-1910,  weeds  were  allowed  to 
grow  on  these  plots.  During  the  winters  of  1910-1911,  1911-1912, 
and  1914-1915,  barley  was  grown,  in  1912-1913,  alfilaria  (Er odium 
cicutarium),  and  during  the  winter  of  1913-1914,  rye  was  used. 


CULTUEE  OF  WINTER  CROPS  GROWN  AS  GREEN  MANURES 

The  soil  was  disked  or  plowed  early  in  September  of  each  year. 
The  clover  seed  was  then  sown  broadcast  and  harrowed  into  the  soil. 
The  other  larger-seeded  crops  were  sown  broadcast  and  harrowed  into 
the  soil  for  the  crops  of  1910,  1911,  1912,  and  1913.  During  the  other 
seasons  a  grain  drill  was  used.  Better  stands  usually  followed  drill- 
ing than  broadcasting.  As  soon  after  sowing  as  possible,  the  land 
was  furrowed  out  for  irrigation.  From  three  to  five  acre-inches  of 
water  was  applied  at  intervals  of  three  to  six  weeks. 

In  the  spring,  the  crop  from  typical  areas  (20  x  20  feet)  in  each 
plot,  was  cut  and  weighed  to  determine  the  tonnage  of  green  tops  at 
time  of  plowing.  The  results  of  these  weighings  are  shown  in  table  II 
where  the  average  tonnage  produced  by  each  green-manure  crop  is 
given.  The  samples  were  cut  at  the  surface  of  the  soil  and  immedi- 
ately weighed.  The  figures  on  tonnage  represent  the  entire  top 
growth  produced  on  the  plots,  as  no  attempt  was  made  to  eliminate 
the  weeds  during  the  growth  of  the  crop  or  at  the  time  of  weighing. 
The  tonnages  produced  are  more  uniform  than  would  have  been  the 
case  had  the  top  growth  of  the  planted  crop  been  weighed  alone. 
Thus  the  tonnages  given  may  be  compared  with  those  obtained  under 
ordinary  field  conditions  where  a  certain  percentage  of  the  crop  is 
made  up  of  the  common  weeds. 

In  late  February  or  early  March,  a  dressing  of  raw  rock  phosphate, 
540  pounds  per  acre,  and  sulphate  of  potash,  324  pounds  per  acre, 
was  uniformly  applied  over  all  plots.      Following  this  operation,  the 


8  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

plots  were  plowed  to  a  depth  of  nine  to  ten  inches.  This  was  usually 
done  with  a  large  eighteen-inch  moldboard  plow  equipped  with 
fourteen-inch  rolling  cutter  and  heavy  weed-chain,  which  completely 
buried  all  of  the  tops. 


CULTURE  OF  SUMMER  CROPS  GROWN  AS  INDICATORS  OF  RELATIVE 
VALUE   OF   VARIOUS   GREEN  MANURES 

Following  the  preparation  of  a  good  seed-bed,  summer  field  crops 
were  planted.  This  was  usually  done  during  the  months  of  March 
or  April,  depending  upon  variety  and  season.  During  the  growth 
of  these  summer  indicator  crops,  applications  of  nitrogen  were  made 
to  the  non-legume  plots,  nos.  2,  6,  10,  and  14. 

The  amounts  and  sources  of  the  nitrogen  added  are  shown  in 
Table  I : 

TABLE  1 

Nitrogenous  Fertilizers  Applied  to  Plots  2,  6,  10,  and  14,  in 
Pounds  per  Acre 

Dried  blood 

Nitrate  of  soda  during 

during  seasons  seasons 

of  1910,  1911,  of  1914  and 

1912,  and  1913,  1915, 

Plot                                                         Treatment                                                         pounds  pounds 

2         Non-legurne  green  manure  and  123  lbs.  N  per  acre         810  900 

6         Non-legume  green  manure  and     41  lbs.  N  per  acre         270  300 

10         Non-legume  green  manure  and  163  lbs.  N  per  acre       1080  1200 

14         Non-legume  green  manure  and     82  lbs.  N  per  acre         540  600 

The  nitrate  of  soda  was  divided  into  two  or  three  applications 
made  during  the  early  development  of  the  indicator  crops.  With  the 
dried  blood  the  entire  amount  was  applied  after  plowing  under  the 
green-manure  crops  and  then  disked  into  the  soil  before  the  planting 
of  the  summer  crops.  During  the  summers  of  1910  and  1911,  cabbage, 
corn,  and  sugar  beets  were  grown  as  summer  indicator  crops.  "With 
each  of  these  three  crops  the  yields  were  heavy,  and  those  of  the  check 
plots  were  reasonably  uniform.  Potatoes  and  corn  served  as  the 
indicator  crops  for  the  season  of  1912.  Potatoes,  corn,  and  sorghum 
were  used  as  the  indicator  crop  in  1913.  The  sorghum  followed  the 
potatoes  which  were  harvested  early  in  June.  During  1914,  corn 
was  used  as  the  summer  indicator  crop.  The  results  of  this  year  were 
satisfactory,  although  the  wireworm  caused  considerable  irregularity 
in  the  stand.  Sudan  grass  was  grown  as  the  indicator  crop  for  1915. 
This  crop  was  sown  broadcast  and  two  cuttings  of  hay  removed. 


GREEN  MANURE  CROPS  IN  SOUTHERN  CALIFORNIA 


L^**    i    iar 


: 


Fig.  2. — A,  Melilotus  clover  plant  (1/10  natural  size).  Note  tendency  to  root 
deeply.  Its  upright  branching  habit  is  shown  in  this  cut.  B,  Partial  root  system 
of  melilotus  clover  plant  (%  natural  size).  Note  large  taproot  and  presence  of 
small  nodules  on  the  fibers. 


10 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


RESULTS    OF    EXPERIMENTS 

YIELDS  OF  DIFFERENT  GREEN-MANURE  CROPS 

Assuming  that  organic  matter  is  of  prime  importance  in  main- 
taining fertility  in  California  soils,  the  value  of  green-manure  crops 
must  be  judged  in  part  by  their  ability  to  produce  heavy  tonnages 
under  average  winter  conditions.  Table  II  gives  the  average  yield 
of  green  matter  produced  by  the  different  green  manures  at  the  time 
they  were  turned  under.  The  tonnages  vary  from  7.5  to  20  tons, 
with  most  of  the  crops  averaging  about  12  tons  of  green  tops  per  acre. 
The  very  heavy  yield  of  purple  vetch  is,  however,  the  average  of  only 
two  years  as  compared  with  a  five-year  average  of  the  other  crops. 


TABLE  II 

Average  Tonnage  and 

Composition  of  Green  Matter 

Turned 

Under  on 

Each  Lot 

Plot 

1 

Green  manure 
;                    crop 

Common  vetch 

Average 
tonnage 
of  green 
manures 
on  acre 
basis 

12.0 

No.  of 
analysis 

25 

Percent- 
age of 
water 

82 

Per  cent 
nitrogen 
in  green 
weight 
.538 

Pounds  of 

nitrogen 

per  ton 

green  tops 

10.8 

Pounds 

nitrogen 

per  acre 

129.6 

2 

Non-legume* 

10.9 

4 

82 

.281 

5.6 

61.0 

3 

Bur  clover 

12.7 

21 

84 

.637 

12.7 

161.3 

4 

Non-legume* 

9.0 

4 

82 

.281 

5.6 

50.4 

5 

Purple  vetcht 

20.0 

5 

81 

.569 

11.4 

228.0 

6 

Non-legume* 

9.7 

4 

82 

.281 

5.6 

54.3 

7 

Vetch 

12.8 

4 

82 

.518 

10.4 

133.1 

8 

Non-legume* 

9.2 

4 

82 

.281 

5.6 

51.5 

9 

Canada  peas 

7.5 

18 

80 

.633 

12.7 

95.2 

10 

Non-legume* 

11.0 

4 

82 

.281 

5.6 

61.6 

11 

Tangier  peas 

13.7 

5 

88 

.494 

9.9 

135.6 

12 

Non-legume* 

8.7 

4 

82 

.281 

5.6 

48.7 

13 

Melilotus  indica 

13.7 

9 

80 

.556 

11.1 

152.0 

14 

Non-legume* 

10.5 

4 

82 

.281 

5.6 

58.8 

15 

Fenugreek 

12.3 

12 

82 

.557 

11.1 

136.5 

16 

Non-legume* 

8.9 

4 

82 

.281 

5.6 

49.8 

17 

Lentils 

12.1 

7 

75 

.650 

13.0 

157.3 

Average  of  nine  legume 

plots 

13.0 

11 

81 

.572 

11.4 

148.2 

Average  of  eight  non- 

legume  plots 

9.7 

4 

82 

.281 

5.6 

54.3 

*  Non-legume  tonnages  and  compositions  are  averages  of  barley,  rye,  and  alfilaria. 

t  Purple  vetch  was  grown  but  two  years. 

X  The  author  is  indebted  to  Professor  J.  H.  Norton  and  Messrs.  H.  D.  Young  and 
E.  E.  Thomas  for  most  of  the  analyses  from  which  the  averages  contained  in  this  table 
were  computed. 


GREEN   MANURE  CROPS  IN  SOUTHERN   CALIFORNIA 


11 


Fig.  3. — A,  partial  root  systems  of  purple  vetch  (%  natural  size).  Note  the 
number  of  lateral  fibers  and  absence  of  any  well  defined  taproot.  B,  Partial  root 
system  of  Canada  pea  i1/^  natural  size).  Note  large  size  of  nodules  characteristic 
of  this  plant.  This  is  not,  however,  an  indication  that  more  nitrogen  is  being 
taken  from  the  air. 


12  UNIVERSITY  OF   CALIFORNIA — EXPERIMENT  STATION 

Although  no  records  were  made  of  the  percentage  of  weeds  present 
in  the  various  green  manure  crops,  there  were  very  noticeable  differ- 
ences in  this  regard.  The  common  vetch  was  always  badly  infested 
with  the  western  pigweed  (Chenop odium  murale).  To  a  lesser  extent 
this  was  also  true  of  Vicia  ervilia  and  fenugreek.  During  the  last 
three  years  of  the  experiment,  the  stand  of  Tangier  peas  was  poor 
and  thus  enabled  weeds  to  get  a  foothold  on  Plot  II. 

The  common  vetch  was  seriously  affected  with  the  green  pea  aphis 
during  the  winters  of  1911-12  and  1912-13.  Bur  clover  was  slow 
in  its  early  development  and  was  thus  unable  to  smother  out  the  weeds 
as  satisfactorily  as  certain  others.  The  fenugreek  gave  poor  results 
during  several  winters  from  causes  not  understood.  It  is  naturally 
a  smaller  growing  plant  than  the  others  and  seemed  less  able  to  with- 
stand adverse  temperature  and  moisture  conditions.  Lentils  gave 
good  yields  of  green  tops  during  the  first  two  seasons,  but  later 
suffered  from  a  root  disease.  Canada  field  peas  gave  good  yields  and 
pure  stands  during  the  first  two  years,  but  later  the  yields  were 
markedly  reduced  by  aphis  injury,  poor  germination  and  frost.  The 
newly  introduced  bitter  vetch  (Vicia  ervilia)  gave  better  stands  than 
the  common  variety,  but  was  not  sufficiently  vigorous  to  smother  the 
weeds.  Purple  vetch,2  like  the  foregoing  variety,  is  a  recent  intro- 
duction of  the  United  States  Department  of  Agriculture.  This 
variety  gave  very  heavy  yields  for  the  two  years  tested  and  seemed 
able  entirely  to  smother  weeds.  Melilotus  indica  gave  more  uniform 
results  as  to  stand  than  any  other  variety  tested.  Nothing  seemed  to 
affect  it  materially,  its  most  serious  disadvantage  being  its  slow  early 
development.  It  was  more  easily  handled  in  the  spring  because  of 
its  upright  habit  and  was  not  seriously  damaged  by  the  tramping 
necessary  in  orchard  heating.  Temperatures  as  low  as  16°  F., 
although  checking  its  development,  did  not  injure  it  as  was  the  case 
with  all  other  varieties  except  bur  clover. 


COMPOSITION"  OF  DIFFERENT   GREEN-MANURE   CROPS 

Table  II  also  gives  the  average  nitrogen  content  of  the  crops  used 
as  green  manures  in  the  experiments  which  includes  several  of  those 
most  commonly  used  in  southern  California.  The  nitrogen  content 
is  based  on  the  green  weight  of  the  tops  at  time  of  plowing. 


2  The  author  is  especially  indebted  to  Professor  Roland  McKee,  Assistant 
Agrostologist,  U.  S.  D.  A.,  Bureau  of  Plant  Industry,  for  his  active  cooperation 
in  furnishing  seed  of  the  Tangier  pea,  purple  vetch,  and  bitter  vetch  (V.  ervilia). 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA 


13 


The  percentage  of  nitrogen  shown  in  these  analyses  indicates  that 
with  the  legumes  a  considerable  portion  of  the  nitrogen  they  contain 
must  have  been  derived  from  the  air,  since  on  the  same  soil,  from 
two  to  three  times  as  much  nitrogen  had  gone  into  the  tissues  of  the 
legumes,  as  was  the  case  with  the  non-legumes.  This  is  further  borne 
out  by  the  analyses  of  the  soils  of  the  various  plots.  The  soil  was 
sampled  during  January,  1914,  while  the  crops  were  still  growing, 
thus  representing  the  soil's  condition  as  to  nitrogen  before  that  con- 
tained in  the  green  crop  had  been  returned  to  it.      The  average  of 


Fig.  4. — Showing  yields  of  corn  on  plots  10,  12,  and  13,  for  the  season  1912: 
10,  barley  plowed  under  and  108  pounds  of  nitrate  of  soda  added;  12,  barley 
plowed  under — no  fertilizer;  13,  bitter  clover  (Melilotus  indica)  plowed  under — no 
fertilizer. 


fifteen  analyses  of  the  legume  plots  showed  a  total  nitrogen  content 
of  .032  per  cent,  while  the  average  of  eight  analyses  of  the  non-legume 
plots  shows  a  content  of  .027  per  cent  nitrogen.  Since  these  samples 
were  taken  to  a  depth  of  two  feet,  this  difference  of  .005  per  cent 
of  nitrogen  represented  an  apparent  gain  of  400  pounds  nitrogen 
per  acre. 

Table  III  gives  the  average  yields  of  the  six  indicator  crops  for 
each  plot  on  the  acre  basis.  The  figures  in  italics  are  the  yields  of 
the  unfertilized  non-legume  plots  where  the  green  manure  crop  was 
rye  or  barley.      The  yield  of  the  four  unfertilized  non-legume  plots 


14 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


are  uniformly  low  when  compared  with  those  of  the  plots  where 
legumes  had  been  turned  under  or  where  nitrogenous  fertilizer  had 
been  applied  to  the  non-legume  plots.  It  is  significant,  however,  that 
the  low  yields  on  the  unfertilized  non-legume  plots  are  practically 
equal  to  the  state  average  for  these  crops. 

Table  IV  gives  the  percentage  of  increase  in  yield  of  the  legume 
plots,  and  those  receiving  nitrogen  additions  over  those  where  non- 
legume  green  manures  were  used  alone.  These  figures  were  obtained 
by  comparing  the  yield  of  each  plot  where  legumes  had  been  turned 


Fig.  5. — Showing  yields  of  corn  on  plots  1,  4,  and  5  for  the  season  of  1912: 
1,  common  vetch  plowed  under — no  fertilizer;  4,  barley  plowed  under — no  ferti- 
lizer;  5,  purple  vetch  plowed  under — no  fertilizer. 


under,  with  the  yield  of  the  adjacent  unfertilized  non-legume  plot. 
The  increases  noted  on  plots  2,  6,  10,  and  14,  were  obtained  by  com- 
paring these  plots  fertilized  with  nitrogen  with  the  average  of  the 
yields  of  the  two  nearest  unfertilized  non-legume  plots.  Thus  Plot 
13,  where  a  green-manure  crop  of  Melilotus  indica  had  been  turned 
under,  was  compared  in  yield  with  that  of  the  unfertilized  non-legume 
Plot  12.  The  yield  of  Plot  10,  which  had  non-legumes  turned  under 
and  nitrogenous  fertilizer  applied,  was  compared  with  the  average 
of  the  yields  on  the  unfertilized  non-legume  plots  8  and  12. 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA 


15 


Very  marked  effects  are  noted  in  the  great  majority  of  the  cases 
where  a  commercial  nitrogenous  fertilizer  was  used  in  addition  to 
rye  or  barley  green  manure  (fig.  4).  With  the  exception  of  Plot  2, 
the  amount  of  increase  was  roughly  in  proportion  to  the  amount  of 
nitrogen  added.  Where  41  pounds  of  nitrogen  was  added,  the  average 
increase  was  12.8  per  cent ;  with  82  pounds,  30  per  cent  increase ;  and 
with  163  pounds,  51  per  cent  increase. 

Striking  results  are,  however,  noticed  on  plots  where  legumes  were 
used  as  green  manures  (fig.  5). 


TABLE  III 

Yields  Following 

Various 

Soil  Treatments  in 

Pounds 

per  Acre 

Plot 

Treatment 

Shelled 
corn, 
5-yr. 
aver. 

Potatoes, 
2-yr. 
aver. 

Cabbage,  t 
2-yr. 
aver. 

Beets, 
2-yr. 
aver. 

Sorghum 
hav, 
1913 

Sudan 
grass 
hay.t 
1915 

1 

Common  vetch 

2,125 

10  243 

30,640 

8,363 

2 

Non-legume  +  123 

lbs.  N 
Bur  clover 

2,046 
2,135 

11,504 
13,671 

32,106 
34,748 

11,580 
9,489 

16  245 

3 

11,689 

14,079 

4 

Non-legume    (check) 

1,693 

9,275 

10,639 

26,878 

7,505 

13  395 

5* 

Purple  vetch 

Non-legume  4-  41 

3091 

17470 

6 

lbs.  N 

1,929 

9  982 

11,714 

25,048 

9,114 

16,615 

7 

Vicia  ervilia 

2,293 

13,874 

18,139 

36,888 

9,516 

16,957 

8 

Non-legume   ( check ) 

1,550 

9,942 

10  314 

21,476 

8,792 

13,908 

9 

Canada  peas 

2  235 

14,600 

15,571 

35,270 

11,231 

15,789 

10 

Non -legume  +  163 

lbs.  N 

2,462 

13,103 

15,108 

34,424 

12  733 

20  320 

11 

Tangier  peas 

2,523 

13,607 

16,405 

41,192 

12,250 

17,841 

12 

Non-legume   (check) 

1.617 

9  823 

7,678 

24,687 

7,881 

15,988 

13 

Melilotus  indica 

'2,754 

15,115 

19  835 

47,300 

11,607 

19,038 

14 

Non-legume  +  82 

lbs.  N 

2,395 

12,256 

13,024 

31,388 

11,770 

20,206 

15 

Fenugreek 

2,652 

15,322 

13,208 

33,567 

10,374 

19,038 

16 

Non-legume   (check) 

1973 

9  887 

11,865 

25,362 

9  971 

16  359 

17 

Lentils 

2  569 

12,268 

12,793 

38,931 

12,224 

16,800 

Aver. 

of  legume  plots 

2,486 

13,588 

15,377 

37,317 

10,632 

17,126 

Aver. 

of  non-legume  plots 

fertilized  with   an   aver- 

age 

i  of  102  lbs.  nitrogen 

2  208 

11,711 

13,282 

30,741 

11,299 

18,346 

Aver. 

of  unfertilized   non- 

legume  plots 

1,708 

9,732 

10,124 

24,601 

8,537 

14,912 

*  Purple  vetch  was  grown  as  green-manure  crop  during  the  years  1914  and  1915  only. 

t  Cabbage  on  Plots  1  and  2  was  so  seriously  injured  by  rabbits  that  the  yields  of 
these  plots  cannot  be  taken  into  consideration  in  getting  the  average. 

t  Sudan  grass  was  such  a  poor  stand  on  Plot  1  that  it  was  thrown  out  of  the  experi- 
ment. 


16 


UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 


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GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  17 

The  use  of  Meliotus  indica  as  a  green-manure  crop  resulted  in  a 
gain  over  adjacent  non-legume  plots  of  nearly  twenty  bushels  of 
shelled  corn  per  acre.  This  is  certainly  indicative  of  the  manurial 
value  of  this  plant.  With  the  other  five  indicator  crops,  a  marked 
increase  is  also  noted.  Not  only  did  such  results  follow  the  use  of 
Melilotus  indica  as  a  green-manure  crop,  but  to  a  greater  or  less  extent 
the  same  was  true  following  the  other  legumes. 

The  fact  that  different  crops  were  used  necessitates  the  showing  of 
the  average  increases  in  percentages  rather  than  in  pounds  or  tons. 
The  column  to  the  extreme  right  in  table  4  gives  the  average  increase 
of  all  crops  for  each  of  the  plots  where  nitrogen  additions  have  been 
made  either  from  commercial  fertilizers  or  from  the  air  through  the 
agency  of  legumes. 

The  nine  legume  plots  show  an  average  percentage  of  increase  over 
the  non-legume  plots  of  approximately  37  per  cent,  while  a  like  aver- 
age of  the  four  cereal  plots  where  nitrogen  has  been  added  each  year 
at  an  average  rate  of  102  pounds  per  acre  shows  only  a  30  per  cent 
increase  in  yield.  It  is  significant  that  the  non-legume  plot  receiving 
nitrogen  at  the  rate  of  163  pounds  per  acre,  gave  for  the  six  years 
an  average  increase  of  51  per  cent,  while  the  plot  where  Melilotus 
indica  was  used  as  a  green  manure,  shows  an  increase  of  57  per  cent 
without  the  addition  of  any  nitrogenous  fertilizer. 


SUMMARY 

A  number  of  legumes  make  satisfactory  growth  when  used  as 
winter  green  manures  in  southern  California.  Of  these,  Melilotus 
indica  is  the  most  promising ;  others  of  value  are  common  vetch,  bur 
clover,  and  Canada  peas.  Fenugreek  and  lentils  cannot  be  depended 
upon  to  give  heavy  yields  and  the  seed  is  expensive.  Purple  vetch, 
Tangier  peas,  and  bitter  vetch  (Vicia  ervilia)  possess  advantages  over 
most  of  the  other  varieties  tried,  but  there  is  as  yet  no  seed  available  in 
commercial  quantities.  From  the  standpoint  of  tonnage  alone,  rye 
and  barley  have  both  given  heavy  yields  in  time  for  spring  plowing. 

The  incorporation  of  the  legume  green  manures  resulted  in  much 
heavier  yields  of  the  summer  field  crops,  than  followed  the  non-legume 
green  manures.  The  average  yields  of  all  legume  plots  when  com- 
pared with  that  of  the  non-legume  plots  show  the  following  increases 
in  yields  from  legume  green  manures;  with  corn,  45  per  cent,  or 
fourteen  bushels  per  acre;  with  potatoes,  39  per  cent,  or  sixty-two 
bushels ;  with  cabbage,  44  per  cent,  or  two  and  a  half  tons ;  with  beets, 


18  UNIVERSITY  OF  CALIFORNIA EXPERIMENT  STATION 

43  per  cent,  or  six  tons;  and  with  sorghum  and  Sudan  grass  hays, 
22  per  cent,  or  one  ton  dry  hay.  The  average  for  all  crops  showed 
an  increase  of  37.7  per  cent.  The  cultural  cost  of  growing  the  field 
crops  were  the  same  in  both  cases,  and  if  we  assume  that  the  yields 
on  the  non-legume  plots,  representing  as  they  do  about  the  state  aver- 
age production,  are  sufficient  to  defray  the  actual  producing  cost,  this 
gain  represents  clear  profit. 

The  use  of  nitrate  of  soda  or  dried  blood  resulted  in  marked 
increases  in  yield  when  compared  with  those  obtained  from  the  unfer- 
tilized non-legume  plots.  The  average  increase  with  all  field  crops 
was  30  per  cent.  This  increase  was  brought  about,  however,  at  an 
average  expense  of  from  $30  to  $35  per  acre.  The  value  of  these 
increases  did  not  cover  this  expense  except  in  the  cases  of  cabbage 
and  potatoes.  This  was  true  whether  large  or  small  amounts  of  nitro- 
gen had  been  added.  With  cabbage  and  potatoes,  the  high  value  of 
the  product  made  the  applications  of  relatively  heavy  amounts  of 
nitrogenous  fertilizer  profitable. 


B.      RESULTS    OF   GREEN    MANURES    IN    A    CITRUS    ORCHARD 

OBJECT  OF  EXPERIMENT 

Winter-grown  green-manure  crops  are  largely  used  in  the  citrus 
orchards  of  California.  The  benefits  derived  from  the  growth  of 
legume  manures  in  the  citrus  orchard  are  brought  out  by  a  comparison 
of  four  of  the  twenty-one  plots  of  the  fertilizer  experiment  in  the 
Rubidoux  block  of  the  Citrus  Experiment  Station,  Riverside,  Califor- 
nia. It  is  the  purpose  of  this  discussion  to  bring  out  the  several 
measured  effects  following  the  continued  use  of  stable  manure  (Plot 
F),  stable  manure  and  raw  phosphate  rock  (Plot  0),  and  stable 
manure,  raw  phosphate  rock  and  legume  green  manures  (Plot  U). 
The  unfertilized  trees  (Plot  B)  being  used  as  a  check. 

OUTLINE  OF  EXPERIMENT 

Plots  B  and  F  contain  six  Navel  orange  trees,  six  Valencia  oranges, 
six  Eureka  lemons,  and  six  Lisbon  lemons.  Plot  0  contains  only  four 
of  each  variety,  while  Plot  U  contains  five  trees  of  each  of  the  first 
three  varieties  named,  but  no  Lisbon  lemons.  For  this  reason,  this 
variety  is  not  considered  in  the  discussion.  The  plots  were  so  arranged 
that  they  may  be  irrigated  separately.  The  cultural  operations  were 
carried  on  in  as  uniform  a  manner  as  possible,  considering  the  differ- 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  19 

ential  treatments  which  called  for  the  growth  of  a  winter  legume  on 
Plot  U.  Winter  crops  of  barley  were  grown  and  turned  under  on 
Plots  B,  F,  and  0  during  the  first  six  years  of  the  experiment. 

Table  V  shows  the  fertilizers  applied  during  the  first  ten  years  of 
the  experiment. 


EESULTS 

Table  VI  gives  the  results  of  the  various  treatments  as  measured 
in  terms  of  yield,  grade,  size  of  fruit,  size  of  tree,  and  estimated 
amount  of  the  citrus  disease  known  as  "mottled  leaf." 

Yield. — The  most  noticeable,  thing  in  the  entire  table  is  the  ex- 
tremely low  yield  of  the  unfertilized  Plot  B.  In  fact,  many  of  the 
trees  have  not  yielded  a  single  fruit  for  the  past  two  years.  Their 
appearance  is  characteristic  of  trees  suffering  from  starvation. 

The  effect  of  stable  manure  on  the  yield  is  exceedingly  marked 
in  the  case  of  all  three  varieties.  In  comparing  the  yields  of  Plot  0 
with  those  of  F,  it  is  of  especial  significance  that  the  differences  are 
not  marked,  and  though  favoring  0  in  Navel  oranges  and  lemons, 
they  favor  F  in  Valencia  oranges.  In  fact,  when  considering  these 
yields  as  representing  the  aggregate  of  six  years,  the  differences  can- 
not be  considered  as  beyond  the  limits  of  experimental  error.  The 
effect  of  increasing  the  phosphorous  content  of  the  soil  through  the 
application  of  slag  and  raw  phosphate  rock  seems  at  the  end  of 
seven  years  to  have  had  little,  if  any,  effect  on  the  yields  of  these  trees. 

Assuming  that  the  yields  of  F  and  0  are  virtually  the  same, 
although  0  received  twice  as  much  phosphoric  acid,  it  is  not  probable 
that  the  increase  in  yield  of  U  over  F  and  0  can  be  in  any  large  part 
ascribed  to  the  fact  that  U  received  three  times  as  much  phosphoric 
acid  as  F.  It  is  impossible  to  ascribe  the  above  increase  to  the  manure 
because  the  total  applied  on  U  during  the  first  ten  years  was  forty-six 
tons  less  per  acre  than  that  applied  on  F  or  0.  Neither  can  these 
differences  be  ascribed  to  the  small  applications  of  commercial  fer- 
tilizer which  were  made  during  the  first  three  seasons'  growth  of 
the  trees,  for  at  the  end  of  five  years'  growth  there  was  no  marked 
difference  between  F,  0,  and  U,  as  regards  appearances  or  size.  The 
increase  in  yield  of  Plot  U  over  that  of  F  or  0,  must  be  ascribed 
therefore  to  the  fact  that  Plot  U  consistently  received  green  manures. 
The  roots  of  the  legumes  were  well  inoculated  and  undoubtedly  drew 
upon  the  supply  of  nitrogen  in  the  air,  for  a  part  of  the  nitrogen 
found  in  their  tissues.     Again,  tonnages  of  organic  material  wTere  thus 


20 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


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GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  21 

produced  which  in  their  incorporation  with  the  soil  undoubtedly  in- 
creased its  organic  content  for  a  time  at  least.  Being  green  and 
succulent  at  time  of  plowing  the  material'  rapidly  underwent  decom- 
position, thus  performing  the  functions  of  so-called  "active  organic 
matter,"  and  at  the  same  time  liberating  large  quantities  of  nitrogen 
which  were  temporarily  locked  up  in  the  tissues  of  the  plant  while 
growing  during  the  winter.  Determinations  on  the  nitrogen  trans- 
formations in  these  plots  have  been  made  by  McBeth.3  These  activ- 
ities going  on  during  the  seasons  of  blooming  and  of  setting  fruit  ma}' 
be  in  large  part  responsible  for  the  heavier  yields  obtained  from 
Plot  U  as  compared  with  F. 

Quality 

Heavy  applications  of  nitrogenous  fertilizers,  especially  if  they 
be  bulky,  as  in  the  case  of  stable  manure,  have  been  frequently  con- 
demned because  of  the  belief  that  they  tend  to  produce  coarse  fruit 
of  a  low  commercial  grade.  During  the  seasons  of  1914  and  1915,  the 
fruit  from  these  plots  was  carefully  graded.  The  results  as  given  in 
table  VI  do  not  support  the  theory  mentioned  above,  but  on  the 
contrary  show  as  large  a  percentage  of  high-grade  fruit  on  Plots 
F,  0,  and  U,  as  on  the  check,  and  with  lemons  a  very  marked  advan- 
tage is  evidenced  on  0  and  U.  This  last  is  largely  due  to  the  smaller 
percentage  of  lemons  that  became  tree-ripe  before  reaching  full  size. 
The  column  showing  the  percentage  of  tree-ripe  lemons  on  the  four 
plots  again  points  to  the  general  superiority  of  Plot  U  as  regards 
quality  of  fruit.  The  column  devoted  to  a  comparison  of  the  per- 
centages of  the  desirable  sizes,  shows  an  advantage  in  the  case  of 
Plot  U  as  regards  size  of  fruit,  i.e.,  an  increase  of  17  per  cent  of 
desirable  sizes  in  Navel  oranges,  and  28  per  cent  in  Valencia  oranges. 
Plot  F  and  0  do  not  show  marked  effects  upon  size  of  fruit  from 
their  several  treatments. 

Size  of  Tree 

Vegetative  growth  is  certainly  an  indication  of  vigor  and  health, 
and  with  other  factors  equal,  the  larger  the  tree  the  larger  the  crop. 
Since  marked  differences  existed  in  the  size  of  the  trees  in  the  several 
plots,  a  method  of  getting  the  size  of  tree  by  volume  was  adopted  in 


s  McBeth,  I.  G.,  Eelation  of  transformation  and  distribution  of  the  soil  nitro- 
gen to  the  nutrition  of  citrus  trees.  Jour,  of  Agricultural  Eesearch,  vol.  IX, 
no.  7,  pp.  194-195,  1917. 


22  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 

1914.      A  standard  fumigation  tent  was  used  and  the  volume  cal- 
culated by  means  of  the  Woglum4  formula. 

In  the  columns  on  tree  sizes,  there  is  shown  to  be  a  marked  increase 
in  size  where  fertilizers  were  applied.  Trees  of  all  varieties  are  much 
larger  on  Plots  F,  0,  and  U,  than  on  B,  but  between  F  and  O,  there 
is  no  constant  difference.  Trees  on  F  are  slightly  larger  than  those 
on  0  in  the  case  of  oranges  and  smaller  in  the  case  of  lemons.  This 
fact  again  emphasizes  the  relative  uniformity  of  results  obtained  on 
these  plots  regardless  of  the  difference  in  the  amount  of  phosphate 
fertilizer  applied. 


"Mottled  Leaf" 

Since  the  plots  discussed  have  been  on  a  relatively  uniform  type 
of  soil  and  have  been  handled  as  uniformly  as  the  experiment  per- 
mitted, it  is  at  least  interesting  to  note  the  marked  differences  in  the 
percentage  of  abnormal  mottled  leaves  as  shown  in  the  three  right- 
hand  columns  of  table  VI.  These  figures  were  obtained  by  taking 
the  averages  of  several  estimates  made  by  a  number  of  separate 
investigators  during  the  fall  months  of  the  three  years  mentioned. 

Trees  on  Plot  U  have  consistently  remained  more  normal  as 
regards  leaf  development  than  on  the  other  plots  here  considered.  At 
the  present  writing,  B  stands  as  before,  giving  every  evidence  of 
starvation,  but  not  showing  any  material  increase  in  the  percentage 
of  mottled  leaves.  Plots  F  and  O  show  some  increase  in  the  amount 
of  mottling.  This  is  more  pronounced  on  0  than  on  F,  as  the  two 
plots  are  more  nearly  similar  in  this  regard  than  formerly.  Plot  U 
shows  quite  a  tendency  toward  further  increases  in  mottling  this 
season.  This  is  not  especially  marked  with  the  lemons  and  Navel 
oranges,  but  is  beginning  to  be  pronounced  with  the  Valencias. 


*  Woglum,  R.  S.,  Fumigation  of  citrus  trees.      U.  S.  D.  A.,  Bureau  of  Ento- 
mology, Bui.  90,  Pt.  I,  p.  28. 


GREEN   MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  23 

C.     GENERAL  DISCUSSION 

METHODS  OF  HANDLING 

In  handling  green-manure  crops,  too  little  care  has  usually  been 
taken  to  insure  a  good  stand.  This  is  probably  due  to  a  general  lack 
of  knowledge  of  the  real  value  of  such  crops.  When  the  bitter  clover 
crop  will  duplicate  in  result  applications  of  dried  blood,  costing  $35 
per  acre,  the  question  of  how  to  insure  success  with  the  clover  becomes 
one  of  considerable  importance. 

TIME  OF  SEEDING 

In  the  citrus  grove,  it  is  usually  considered  wise  to  plow  early; 
that  is,  during  February  or  March.  A  good  development  of  any  one 
of  the  legumes  cannot  be  expected  in  less  than  five  months.  Thus, 
it  is  essential  to  sow  the  seed  during  September  or  the  early  part  of 
October.  In  the  case  of  the  annual  field  crops,  such  as  were  grown 
in  this  experiment,  the  green-manure  crops  can  be  planted  after  har- 
vesting of  such  crops  as  corn,  beets,  Sudan  grass,  and  the  like.  With 
late  corn  and  cotton,  the  seed  may  be  sown  with  the  last  cultivation 
and  thus  get  a  much  earlier  development  of  the  legume  than  would 
result  from  awaiting  the  removal  of  the  crop  before  seeding. 

AMOUNT  OF  SEED  TO  SOW 

The  amount  of  seed  to  sow  will  vary  with  conditions,  such  as  the 
variety  and  the  actual  percentage  of  the  land  planted.  In  young 
orchards  practically  all  the  land  can  be  planted,  while  in  old  orchards 
frequently  less  than  one-half  the  land  is  available.  Since  this  per- 
centage of  available  land  will  vary  so  greatly,  it  is  left  to  each 
grower  to  determine  the  rate  of  seedage.  Taking  all  the  land  into 
consideration,  as  in  a  newly  planted  orchard,  or  after  annual  crops, 
the  following  amounts  of  seed  per  acre  may  be  recommended : 


Crop  Pounds  per  acre 

Melilotus  indica  and  bur  clover 20  —    30 

Fenugreek    35  —    40 

Vetches  70  —    80 

Peas 90  —  100 

Windsor  beans 100  —  200 

Lentils    60—    70 


Average  price  in 
cents  per  pound 

6- 

—  14 

8- 

—  12 

3- 

—    6 

4- 

—    6 

3 

—    6 

9- 

—  11 

24  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


Methods  of  Sowing 

The  preparation  of  the  soil  is  another  important  matter.  The 
small  seeded  species,  such  as  bitter  clover,  demand  a  good  seed-bed 
to  insure  germination.  The  soil  should  be  thoroughly  worked  up  with 
cultivator,  disk-harrow,  or  plow,  following  the  irrigation  preceding 
the  sowing  of  the  seed.  With  bitter  clover,  the  method  that  has 
worked  to  the  best  advantage  has  been  to  broadcast  one-half  the  seed 
on  the  dry  soil  mulch  before  furrowing.  The  soil  should  then  be 
lightly  harrowed  to  cover  the  seed.  After  furrowing,  the  other  half 
of  the  seed  should  be  sown  broadcast  over  the  furrowed  land.  The 
portion  of  the  seed  falling  in  the  furrows  will  be  covered  by  the  sifting 
down  of  the  soil  on  the  sides  of  the  furrow,  when  the  water  is  first 
turned  in.  In  this  way,  a  good  stand  can  be  obtained  in  the  furrow, 
and  if  the  land  is  wet  to  the  surface  between  the  furrows,  a  good 
stand  should  follow  over  all  the  land. 

With  vetches  and  peas  and  all  those  plants  having  relatively  large 
seeds,  the  most  successful  method  has  been  to  irrigate  the  land  and 
follow  as  quickly  as  possible  with  a  cultivator  to  establish  a  loose 
seed-bed.  As  soon  as  this  is  completed,  the  seed  should  be  sown  with 
a  drill  to  a  depth  of  from  two  to  three  inches.  Furrowing  should 
follow  the  drilling  in  order  that  no  further  working  of  the  land  be 
required  after  the  seed  has  sprouted. 

Water  Requirements  of  Manure  Crop 

The  question  of  irrigation  is  very  important.  As  a  general  rule, 
it  may  be  said  that  with  a  rainfall  of  fifteen  inches  or  less,  no  green- 
manure  crop  should  be  grown  if  irrigation  water  is  not  available. 
Even  in  some  of  the  irrigated  districts,  the  supply  of  water  during 
the  fall  months  is  not  sufficient  to  keep  both  the  cover  crop  and  the 
trees  in  good  growing  condition.  Under  these  conditions,  the  ques- 
tion of  growing  a  green-manure  crop  is  one  of  getting  more  water. 
However,  the  great  majority  of  orchards  are  so  situated  that  during 
the  cool  fall  and  winter  months  sufficient  water  is  available  to  keep 
both  crops  growing  normally. 

After  the  cover  crop  has  germinated,  it  is  important  to  keep  as 
much  of  the  original  stand  alive  as  is  possible.  From  the  standpoint 
of  the  cover  crop,  light  but  frequent  irrigations  are  best.  However, 
with  many  growers,  it  is  impossible  to  get  water  more  frequently  than 
once  every  thirty  days.  Under  this  condition,  in  the  interior  valleys, 
it  is  often  wise  to  wait  until  the  latter  part  of  September  or  the  first 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  25 

of  October  to  plant,  in  order  to  miss  the  excessive  heat  so  often 
experienced  during  September.  Since  the  rains  do  not  usually 
begin  until  December,  from  two  to  four  irrigations  of  the  green- 
manure  crop  are  ordinarily  required. 

The  distance  between  the  furrows  is  also  an  important  item  in  the 
irrigation  of  these  crops.  On  the  lighter  soils,  the  furrows  should  be 
made  close  together,  from  eighteen  to  thirty  inches  apart;  while  on 
the  heavier  types  the  distance  may  be  greater  and  yet  permit  of  the 
surface  becoming  wet  between  the  furrows. 

Incorporation  or  Green  Manures  with  the  Soil 

After  having  grown  the  crop,  it  is  all-important  to  incorporate 
it  properly  with  the  soil,  for  only  by  so  doing  is  it  possible  to  get  the 
greatest  benefit  from  its  use.  Unless  the  crop  is  worked  into  the  soil 
before  the  rains  have  ceased,  it  is  highly  advisable  to  turn  the  crop 
under  deeply.  In  fact,  even  when  a  rain  or  two  follows  the  turning- 
under  of  the  crop,  only  a  small  part  of  the  plant  food  can  possibly 
be  washed  down  to  the  roots,  as  in  this  short  time  only  a  portion  of  it 
can  have  been  broken  down  and  become  soluble.  That  portion  of 
the  crop  which  lies  in  the  cultivated  surface  soil  after  the  rains  have 
ceased  can  be  of  but  very  little  value  to  the  growing  crop.  With 
furrow  irrigation,  it  is  practically  impossible  to  carry  down  the  soluble 
fertilizer  salts  that  are  in  the  soil  above  the  level  of  the  water  in  the 
bottom  of  the  furrow.5 

Again,  the  high  temperatures  and  excessive  aeration  of  the  culti- 
vated surface  soil  are  very  exhaustive  of  organic  material.  The 
cultivation  of  the  soil  at  such  frequent  intervals  as  is  commonly 
practised  does  not  permit  of  root  development  into  this  surface  soil. 
Thus  for  a  variety  of  reasons,  it  seems  advisable  to  turn  under 
manures,  whatever  be  their  nature,  to  a  depth  somewhat  in  excess  of 
the  depth  to  which  the  soil  is  cultivated  (figs.  6  and  7).  Thus,  if  it 
is  necessary  to  cultivate  five  or  six  inches  deep  in  order  to  conserve 
water,  plowing  should  be  done  to  a  depth  of  from  seven  to  ten  inches, 
depending  upon  the  character  of  the  soil  and  amount  of  surface  roots. 
Experience  has  apparently  shown  that  the  cutting  of  the  last  year's 
surface  growth  of  feeding  roots  does  no  serious  damage  to  the  tree, 
at  least  when  quantities  of  organic  material  are  by  this  means  made 
available  to  the  new  feeders  which  will  very  soon  occupy  the  level 
between  the  cultivated  surface  and  the  bottom  of  the  plow  furrow. 


5  McBeth,  I.  G.,  Eelation  of  transformation  and  distribution  of  soil  nitrogen 
to  the  nutrition  of  citrus  trees.  Jour,  of  Agricultural  Eesearch,  vol.  IX,  no.  7,  p. 
251,  1917. 


26 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


In  fact,  Plot  U,  which  is  shown  in  table  VI  to  be  one  of  the  best 
plots  in  the  Station  orchard,  has  been  consistently  plowed  ten  inches 
deep  each  year.  A  mass  of  feeding  roots  have  been  cnt  every  year, 
but  within  sixty  days  new  feeders  have  largely  taken  their  place.  It 
is  still  more  significant  that  the  first  growth  in  the  spring  has  been 


Fig.  6. — A,  18-inch  moldboard  plow  used  to  turn  under  heavy  green  manure 
crops.  Note  rolling  coulter  and  weed  chain.  These  permit  the  plow  to  cover  the 
material  much  more  completely  than  would  otherwise  be  possible.  B,  Showing 
plow  seen  in  A  turning  under  a  green  manure  crop  taller  than  the  horses'  backs. 
Note  how  completely  the  tops  are  buried.  The  absence  of  a  slick  furrow  slice  or 
the  presence  of  clods  shows  this  land  to  be  in  proper  condition  for  plowing. 

noticeably  larger-leaved  and  more  vigorous  than  in  the  other  plots. 
This  seems  to  indicate  that  the  locating  of  the  manures  within  easy 
reach  of  the  feeding  roots  much  more  than  overcomes  the  losses  due 
to  the  root  pruning  at  the  time  of  plowing. 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  27 

In  the  case  of  large  plantings  and  a  relatively  short  period  for 
plowing,  a  disk-harrow  may  be  used  advantageously  to  cut  up  the 
green-manure  crop  and  establish  a  mulch  to  prevent  the  drying  out 
of  the  soil  until  the  plow  can  finish  the  work.  At  times  the  antici- 
pated late  rains  do  not  materialize.  In  this  case,  the  land  should  be 
irrigated  before  plowing,  since  nothing  is  more  exhaustive  of  time  and 
energy  than  to  attempt  to  turn  under  a  heavy  manure  crop  after 
the  soil  has  become  dry.  In  fact,  this  practice  may  injure  the  trees 
to  such  an  extent  as  to  affect  the  set  of  fruit  markedly  for  that  season. 

The  cultivations  of  the  soil  following  the  turning-under  of  a 
manure  crop  should  be  done  with  a  disk  or  knife  harrow  in  order 
that  the  organic  material  may  not  be  pulled  out  on  the  surface  again. 
Usually  in  from  six  to  eight  weeks,  the  regular  cultivators  may  be 
used,  although  in  some  soils  there  seems  to  be  advantages  in  the  disk 
and  knife  harrows,  solely  apart  from  their  ability  to  operate  in  a 
soil  full  of  bulky,  organic  material. 


INOCULATION  OF  LEGUMES 

All  legumes  have  the  power  of  utilizing  certain  amounts  of  nitro- 
gen from  the  air  when  their  roots  are  infected  with  certain  species 
of  bacteria.  These  bacteria  form  colonies  at  various  points  along  the 
roots.  The  enlargements  of  the  roots  to  accommodate  these  colonies 
are  commonly  called  nodules  and  are  familiar  to  all  who  have  exam- 
ined the  roots  of  legumes  (vetches,  and  the  like)  (figs.  1  and  2). 
Without  the  colonies  of  bacteria  on  the  roots,  a  legume  cannot  draw 
upon  the  supply  of  nitrogen  in  the  air.  It  is  thus  of  vital  importance 
to  have  the  legume  roots  properly  inoculated  if  they  are  to  be  used 
as  green  manures  to  add  nitrogen  from  the  air.  Without  the  bacteria 
on  the  roots,  legumes  can  add  no  nitrogen  to  the  soil  and  are  no 
better  than  barley  or  rye  in  this  regard. 

All  of  the  nine  varieties  of  legumes  tested  in  the  experiment  just 
outlined  were  very  well  inoculated  by  organisms  native  to  the  soil. 
In  fact,  this  was  the  case  the  first  year  they  were  sown  on  virgin 
brush  land.  Artificial  inoculations  on  this  soil  have  shown  no  appar- 
ent increase  in  number  of  nodules  or  in  vigor  of  plants.  Observations 
made  over  several  of  the  southern  counties  have  in  most  cases  shown 
the  same  general  condition.  The  natural  flora  of  the  land  contains 
a  large  variety  of  legumes,  which  are  well  inoculated  and  which  seem 
to  carry  the  necessary  varieties  of  bacteria  to  suit  all  of  the  legume 
crops  tested. 


28 


UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


MINOR  ADVANTAGES  OF  GREEN-MANUKE  CROPS 

The  growth  of  winter  green-manure  crops  may  bring  about  savings 
totally  distinct  from  those  already  mentioned.  In  many  sections, 
the  winter  rains  are  spasmodic,  coming  down  at  times  very  heavily. 
Since  many  orchards  are  located  on  the  sloping  land  of  the  low  foot- 
hills, such  heavy  rains  are  apt  to  do  much  damage  in  washing  away 
the  top  soil.  Green-manure  crops  growing  during  the  season  of 
heaviest  rainfall,  give  almost  complete  protection  from  such  losses. 


r% 


* 


fKl.s    y.4k%*t£ 


Fig 


7. — Showing  the  appearance  of  the  land  immediately  after  plowing  seen  in 
figure  6.     Note  the  total  absence  of  organic  matter  on  the  surface. 

In  fact,  many  growers  would  not  dare  to  leave  their  groves  in  a  clean 
cultivated  condition  during  the  winter  for  this  reason  alone.  In  this 
sense,  the  green-manure  crop  becomes  a  true  cover  crop  protecting  the 
soil  from  physical  losses. 

The  use  of  a  legume  manure  crop  to  increase  the  nitrogen  supply 
in  the  soil  has  already  been  discussed  from  the  standpoint  of  the 
nitrogen  additions  from  the  air.  There  is,  however,  another  factor 
involved  in  the  maintenance  of  an  ample  supply  of  nitrogen  in  the 
root-feeding  area  of  the  soil.  Nitrogen  in  the  forms  available  to 
plants  is  extremely  soluble  and  thus  is  very  easily  carried  by  water. 
During  nearly  every  winter,  there  are  one  or  more  very  heavy  rains 


GREEN   MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  29 

which  with  the  soil  already  wet  from  the  irrigations  may  soak  down 
to  depths  of  ten  to  twenty  feet.  This  water  strikes  the  surface  first 
and  the  soluble  nitrates,  frequently  very  abundant  in  the  upper  three 
to  six  inches,  go  into  solution  and  as  further  rain  falls,  that  which 
fell  first  is  gradually  pushed  downward,  still  carrying  the  nitrates 
taken  up  along  the  way.  Thus  the  rains  wetting  the  soil  very  deeply 
tend  to  leach  out  of  the  surface  soil  large  quantities  of  available 
nitrogen.  This  loss  may  be  very  heavy,  as  evidenced  by  work  carried 
on  by  Dr.  I.  G.  McBeth0  on  the  movement  of  nitrates.  A  green- 
manure  crop  growing  during  the  rainy  season  takes  up  a  very  large 
proportion  of  the  available  nitrogen  in  the  soil,  and  water  passing 
through  a  soil  on  which  a  vigorous  crop  is  growing,  finds  little  soluble 
plant  food  to  carry  to  depths  beyond  the  reach  of  roots.  In  the 
incorporation  of  the  green-manure  crop,  this  stored  nitrogen  is  again 
added  to  the  soil  and  is  rapidly  made  available  to  plants  through  the 
decomposition  which  begins  immediately  if  the  soil  is  moist  at  the 
time  of  plowing. 

Most  of  legumes  used  as  green  manures  are  relatively  deep-rooting. 
Roots  of  Melilotus  indica  have  been  found  to  the  depth  of  eight  feet 
in  a  citrus  orchard  (figs.  1  and  2).  The  annual  decay  of  a  multitude 
of  these  roots  undoubtedly  has  a  marked  effect  on  the  capacity  of  the 
soil  to  take  up  water.  Under  irrigated  conditions,  many  soils  develop 
irrigation  hardpan  from  the  sifting  downward  of  the  finer  particles 
of  soil,  and  with  constant  cultivation,  winter  and  summer,  this  layer 
may  become  so  compact  that  air  and  water  will  penetrate  it  with 
difficulty.  The  annual  growth  of  green-manure  crops  tends  to  lessen 
this  condition,  since  cultivation  as  one  of  the  contributing  causes  is 
done  away  with  during  six  months  of  each  year.  The  decay  of  the 
roots  of  the  crop  also  lessens  the  effect  of  the  hardpan  left  over  from 
the  previous  years. 


McBeth,  I.  G.,  loc.  cit.,  p.  244. 


30  UNIVERSITY  OF   CALIFORNIA EXPERIMENT  STATION 


SUMMARY 

A  number  of  legumes  gave  satisfactory  yields  when  grown  as 
winter  green-manure  crops.  Of  these,  Melilotus  indica  is  the  most 
promising,  both  from  the  standpoint  of  vigor  and  available  supplies 
of  seed.  Extensive  use  shows  it  to  be  well  adapted  to  a  great  variety 
of  conditions.  Purple  vetch  gave  very  heavy  yields  and  is  more 
rapid  in  its  early  development  than  the  Melilotus  indica.  It  should 
be  largely  planted  when  seed  becomes  available  in  sufficient  quantities. 

Bur  clover  did  not  give  as  good  yields  as  Melilotus  and  is  of  value 
mainly  in  sections  and  under  conditions  where  its  early  seeding  habit 
will  permit  of  its  reseeding  itself. 

Fenugreek  is  not  well  adapted  to  use  in  southern  California. 

Spring  vetch  (Vicia  sativa)  and  Canada  peas  are  of  value  in 
certain  sections  where  the  green  pea  aphis  is  not  yet  a  factor. 

Legumes  were  shown  to  be  far  superior  to  non-legumes  as  green- 
manure  crops  when  measured  by  their  effect  on  field  crops  following. 
The  yield  of  a  number  of  crops  following  legume  green  manures 
when  compared  with  those  following  non-legumes  showed  the  follow- 
ing increases :  An  average  increase  with  potatoes  of  39  per  cent ;  with 
corn,  45  per  cent ;  with  cabbage,  44  per  cent ;  with  sugar  beets,  43 
per  cent,  and  with  sorghum  and  Sudan  grass,  25  per  cent  and  18 
per  cent  respectively.  Legumes  alone  gave  as  good  or  better  results 
than  non-leguminous  green-manure  crops  plus  an  annual  application 
of  540  pounds  per  acre  of  nitrate  of  soda. 

Green-manure  crops  have  had  a  marked  effect  on  citrus  trees. 
The  trees  on  the  plot  where  legume  green  manures  have  been  annually 
turned  under  are  superior  in  every  way  to  those  similarly  fertilized, 
where  no  leguminous  green  manure  has  been  used.  Green  manuring 
has  resulted  in  a  30  per  cent  increase  in  size  of  tree.  The  total  yields 
at  the  age  of  ten  years  were  68  per  cent  greater  on  the  green-manured 
plot.  Not  only  was  more  fruit  produced,  but  the  proportion  of  fancy 
and  choice  fruit  was  larger.  Green  manuring  had  a  marked  effect 
upon  the  size  of  the  fruit,  there  being  63  per  cent  more  of  the  desirable 
sizes  (150s,  176s  and  200s)  than  on  the  plots  not  green-manured. 
The  trees  where  legume  green  manures  had  been  used  were  in  much 
better  health,  as  evidenced  by  the  fact  that  only  3  per  cent  of  the 
leaves  were  "mottled"  during  the  seasons  of  1912,  1913  and  1914, 
while  on  plots  similarly  fertilized,  where  legumes  had  not  been  used, 
the  average  was  13.5  per  cent. 


GREEN  MANURE  CROPS  IN  SOUTHERN   CALIFORNIA  31 

Green  manures  have  additional  values  in  that  their  growth  during 
the  winter  months  prevents  serious  washing  of  the  soil  during  heavy 
rains. 

Large  amounts  of  nitrogen  are  saved  from  leaching  below  the 
limits  of  roots  by  growing  winter  green-manure  crops  which  utilize 
the  excess  nitrogen  and  hold  it  until  spring  when  they  are  plowed 
under.  The  decay  of  the  roots  of  the  crop  tends  to  make  the  soil 
more  open  to  the  access  of  air  and  water. 

Green-manure  crops  should  be  sown  during  September  or  October, 
if  satisfactory  yields  are  expected  by  February  or  March. 

The  small-seeded  legumes,  such  as  Meliloins  indica  and  bur  clover, 
have  given  good  stands  when  broadcasted  before  irrigation.  Vetches 
and  other  large-seeded  legumes  gave  better  results  when  planted  with 
a  drill  after  irrigation  and  subsequent  cultivation,  than  when  broad- 
casted before  irrigation. 

Irrigation  is  usually  required  to  grow  satisfactory  tonnages  of  the 
legume  green  manure  crops.  When  planted  in  September  or  October, 
from  three  to  six  acre-inches  of  water  are  required  to  carry  the  crop 
until  rains  begin.  With  late  sowings,  rains  may  sometimes  be  de- 
pended upon  to  start  the  crop,  but  in  this  case  irrigation  is  usually 
required  to  carry  the  crop  to  full  development  in  the  spring  and  to 
enable  the  crop  to  be  properly  incorporated  in  the  soil. 

Green-manure  crops  may  be  expected  to  give  most  satisfactory 
results  when  plowed  under  to  a  depth  of  from  seven  to  ten  inches. 
They  should  never  be  plowed  under  when  the  land  is  dry,  as  this 
will  result  in  poor  incorporation  of  the  green  tops  and  slow  decay. 
With  field  crops,  moist  plowing  is  an  absolute  necessity  if  a  proper 
seed-bed  is  to  be  obtained  before  planting  the  summer  crop. 

Artificial  inoculation  is  seldom  necessary  in  southern  California 
orchards  with  the  winter-growing  legumes  in  common  use. 


STATION  PUBLICATIONS  AVAILABLE  FOR  FREE  DISTRIBUTION 


REPORTS 
1897.      Resistant  Vines,  their  Selection,   Adaptation,   and  Grafting.      Appendix  to  Viticultural 
Report  for  1896. 

1902.  Report   of  the  Agricultural   Experiment   Station   for   1898-1901. 

1903.  Report   of   the   Agricultural   Experiment   Station   for    1901-03. 

1904.  Twenty-second  Report  of  the  Agricultural  Experiment  Station  for  1903-04. 

1914.  Report  of  the  College  of  Agriculture  and  the  Agricultural  Experiment  Station. 

1915.  Report  of  the  College  of  Agriculture  and  the  Agricultural  Experiment   Station. 

1916.  Report  of  the  College  of  Agriculture  and  the  Agricultural  Experiment  Station. 

1917.  Report  of  the  College  of  Agriculture  and  the  Agricultural  Experiment   Station. 

BULLETINS 


No. 
230. 
241. 
242. 
246. 
248. 

250. 
251. 


253. 

255. 
257. 
261. 

262. 

263. 
264. 
265. 
266. 

267. 

268. 
270. 


No. 
113. 
114. 
115. 
121. 

124. 
126. 
127. 
128. 
129. 
181. 
133. 
135. 
136. 
137. 
138. 
139. 


140. 


142. 

1  43. 

144. 
147. 
148. 
150. 
151. 
152. 


153. 
154. 
155. 


Enological  Investigations. 

Vine  Pruning  in  California,  Part  I. 

Humus  in  California  Soils. 

Vine  Pruning  in  California,   Part  II. 

The  Economic  Value  of  Pacific   Coast 

Kelps. 
The  Loquat. 
Utilization  of  the  Nitrogen  and  Organic 

Matter    in    Septic    and    Imhoff   Tank 

Sludges. 
Deterioration  of  Lumber. 
Irrigation   and   Soil   Conditions   in  the 

Sierra  Nevada  Foothills,  California. 
The  Citricola  Scale. 
New  Dosage  Tables. 
Melaxuma     of    the    Walnut,     "Juglans 

regia." 
Citrus   Diseases   of   Florida   and   Cuba 

Compared  with  Those  of  California. 
Size  Grades  for  Ripe  Olives. 
The  Calibration  of  the  Leakage  Meter. 
Cottony  Rot  of  Lemons  in   California. 
A  Spotting  of  Citrus  Fruits  Due  to  the 

Action  of  Oil  Liberated  from  the  Rind. 
Experiments  with  Stocks  for  Citrus. 
Growing  and  Grafting  Olive  Seedlings. 
A  Comparison  of  Annual  Cropping,  Bi- 
ennial Cropping,  and  Green  Manures 

on  the  Yield  of  Wheat. 


No. 

2  71.   Feeding  Dairy  Calves  in  California. 

2  72.   Commercial  Fertilizers. 

2  73.  Preliminary  Report  on  Kearney  Vine- 
yard Experimental  Drain. 

2  74.  The  Common  Honey  Bee  as  an  Agent 
in  Prune  Pollination. 

275.  The  Cultivation  of  Belladonna  in  Cali 
fornia. 

2  76.   The  Pomegranate. 

277.    Sudan  Grass. 

2  78.   Grain   Sorghums. 

2  79.   Irrigation  of  Rice  in  California. 

280.  Irrigation  of  Alfalfa  in  the  Sacramento 
Valley. 

282.  Trials  with  California  Silage  Crops  for 

Dairy  Cows. 

283.  The  Olive  Insects  of  California. 

284.  Irrigation  of  Alfalfa  in  Imperial  Valley. 

285.  The  Milch  Goat  in  California. 

286.  Commercial  Fertilizers. 

288.  Potash  from  Tule  and  the  Fertilizer 
Value  of  Certain  Marsh  Plants. 

290.  The   June   Drop   of  Washington   Navel 

Oranges. 

291.  The  Common  Honey  Bee  as  an  Agent 

in  Prune  Pollination.      (2nd  report.) 


CIRCULARS 


Correspondence  Courses  in  Agriculture. 

Increasing  the  Duty  of  Water. 

Grafting  Vinifera  Vineyards. 

Some  Things  the  Prospective  Settler 
Should    Know. 

Alfalfa   Silage  for  Fattening   Steers. 

Spraying  for  the  Grape  Leaf  Hopper. 

House  Fumigation. 

Insecticide  Formulas. 

The  Control  of  Citrus  Insects. 

Snravinsr  for  Control  of  Walnut  Aphis. 

County  Farm  Adviser. 

Official  Tests  of  Dairy  Cows. 

Melilotus  Indica. 

Wood  Decay  in  Orchard  Trees. 

The  Silo  in   California  Agriculture. 

The  Generation  of  Hydrocyanic  Acid 
Gas  in  Fumigation  by  Portable  Ma- 
chines. 

The  Practical  Application  of  Improved 
Methods  of  Fermentation  in  Califor- 
nia Wineries  during  1913  and  1914. 

Practical  and  Inexpensive  Poultry  Ap- 
pliances. 

Control  of  Grasshoppers  in  Imperial 
Valley. 

Oidium  or  Powdery  Mildew  of  the  Vine. 

Tomato  Growing  in  California. 

"Lungworms." 

Round  Worms   in   Poultry. 

Feeding  and  Management  of  Hogs. 

Some  Observations  on  the  Bulk  Hand- 
ling of  Grain   in  California. 

Announcement  of  the  California  State 
Dairy  Cow  Competition,    1916-18. 

Irrigation  Practice  in  Crowing  Small 
Fruits  in  California. 

Bovine  Tuberculosis. 


No. 

156.  How  to  Operate  an  Incubator. 

157.  Control  of  the  Pear  Scab. 

158.  Home  and  Farm  Canning. 

160.  Lettuce  Growing  in  California. 

161.  Potatoes  in  California. 

162.  White    Diarrhoea    and    Coccidiosis    of 

Chicks. 

164.  Small  Fruit  Culture  in   California. 

165.  Fundamentals    of    Sugar    Beets    under 

California    Conditions. 

166.  The  County  Farm  Bureau. 

3  67.   Feeding   Stuffs  of  Minor  Importance. 

168.  Spraying  for  the  Control  of  Wild  Morn- 

ing-Glory  within  the  Fog  Belt. 

169.  The  1918  Grain  Crop. 

170.  Fertilizing     California     Soils     for     the 

1918  Crop. 
172.  Wheat  Culture. 

174.  Farm   Drainage   Methods. 

175.  Progress  Report  on  the  Marketing  and 

Distribution   of   Milk. 

176.  Hog      Cholera      Prevention      and      the 

Serum  Treatment. 

177.  Grain   Sorghums. 

181.  Control      of     the      California      Ground 

Squirrel. 

182.  Extending  the  Area  of  Irrigated  Wheal 

in   California  for   3  918. 
3  83.   Infectious  Abortion  in  Cows. 

184.  A  Flock  of  Sheep  on  the  Farm. 

185.  Beekeeping   for   the   Fruit-Grower   and 

Small  Rancher,  or  Amateur. 

186.  Poultry  on   the  Farm. 

1 87.  Utilizing  the  Sorghums. 

188.  Lambing  Sheds. 

190.   Agriculture  Clubs  in   California. 
193.    Pruning  the  Seedless  Grapes. 


